update/org.eclipse.update.ui/src/org/eclipse/update/internal/ui/parts/SWTUtil.java

/*
 * (c) Copyright 2001 MyCorporation.
 * All Rights Reserved.
 */
package org.eclipse.update.internal.ui.parts;
/**
 * @version 	1.0
 * @author
 */
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.util.Assert;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Widget;

/**
 * Utility class to simplify access to some SWT resources. 
 */
public class SWTUtil {
	
	/**
	 * Returns the standard display to be used. The method first checks, if
	 * the thread calling this method has an associated disaply. If so, this
	 * display is returned. Otherwise the method returns the default display.
	 */
	public static Display getStandardDisplay() {
		Display display;
		display= Display.getCurrent();
		if (display == null)
			display= Display.getDefault();
		return display;		
	}
	
	/**
	 * Returns the shell for the given widget. If the widget doesn't represent
	 * a SWT object that manage a shell, <code>null</code> is returned.
	 * 
	 * @return the shell for the given widget
	 */
	public static Shell getShell(Widget widget) {
		if (widget instanceof Control)
			return ((Control)widget).getShell();
		if (widget instanceof Caret)
			return ((Caret)widget).getParent().getShell();
		if (widget instanceof DragSource)
			return ((DragSource)widget).getControl().getShell();
		if (widget instanceof DropTarget)
			return ((DropTarget)widget).getControl().getShell();
		if (widget instanceof Menu)
			return ((Menu)widget).getParent().getShell();
		if (widget instanceof ScrollBar)
			return ((ScrollBar)widget).getParent().getShell();
							
		return null;	
	}


	/**
	 * Returns a width hint for a button control.
	 */
	public static int getButtonWidthHint(Button button) {
		PixelConverter converter= new PixelConverter(button);
		int widthHint= converter.convertHorizontalDLUsToPixels(IDialogConstants.BUTTON_WIDTH);
		return Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
	}

	/**
	 * Returns a height hint for a button control.
	 */		
	public static int getButtonHeigthHint(Button button) {
		PixelConverter converter= new PixelConverter(button);
		return converter.convertVerticalDLUsToPixels(IDialogConstants.BUTTON_HEIGHT);
	}	

	
	/**
	 * Sets width and height hint for the button control.
	 * <b>Note:</b> This is a NOP if the button's layout data is not
	 * an instance of <code>GridData</code>.
	 * 
	 * @param	the button for which to set the dimension hint
	 */		
	public static void setButtonDimensionHint(Button button) {
		Assert.isNotNull(button);
		Object gd= button.getLayoutData();
		if (gd instanceof GridData) {
			((GridData)gd).heightHint= getButtonHeigthHint(button);
			((GridData)gd).widthHint= getButtonWidthHint(button);		 
		}
	}		
	

}